In a typical cellular radio system, wireless terminals, also known as mobile stations and/or user equipment units (UEs), communicate via a radio access network (RAN) to one or more core networks. The radio access network covers a geographical area which is divided into cell areas, with each cell area being served by a base station, e.g., a radio base station (RBS), which in some networks may also be called, for example, a “NodeB” (UMTS) or “eNodeB” (LTE). A cell is a geographical area where radio coverage is provided by the radio base station equipment at a base station site. Each cell is identified by an identity within the local radio area, which is broadcast in the cell. Another identity identifying the cell uniquely in the whole mobile network is also broadcasted in the cell. The base stations communicate over the air interface operating on radio frequencies with the user equipment units (UE) within range of the base stations.
In some versions of the radio access network, several base stations are typically connected, e.g., by landlines or microwave, to a controller node, such as a radio network controller (RNC) or a base station controller (BSC), which supervises and coordinates various activities of the plural base stations connected thereto. The radio network controllers are typically connected to one or more core networks.
The Universal Mobile Telecommunications System (UMTS) is a third generation mobile communication system, which evolved from the second generation (2G) Global System for Mobile Communications (GSM). The UMTS terrestrial radio access network (UTRAN) is essentially a radio access network using wideband code division multiple access for user equipment units (UEs). In a forum known as the Third Generation Partnership Project (3GPP), telecommunications suppliers propose and agree upon standards for third generation networks and UTRAN specifically, and investigate enhanced data rate and radio capacity. Specifications for the Evolved Packet System (EPS) have completed within the 3rd Generation Partnership Project (3GPP) and this work continues in the coming 3GPP releases. The EPS comprises the Evolved Universal Terrestrial Radio Access Network (E-UTRAN), also known as the Long Term Evolution (LTE) radio access, and the Evolved Packet Core (EPC), also known as System Architecture Evolution (SAE) core network. E-UTRAN/LTE is a variant of a 3GPP radio access technology wherein the radio base station nodes are directly connected to the EPC core network rather than to radio network controller (RNC) nodes. In general, in E-UTRAN/LTE the functions of a radio network controller (RNC) node are distributed between the radio base stations nodes, e.g., eNodeBs in LTE, and the core network. As such, the radio access network (RAN) of an EPS system has an essentially “flat” architecture comprising radio base station nodes without reporting to radio network controller (RNC) nodes.
One type of wireless terminal is a fixed wireless terminal (FWT) which provides fixed wireless access to other communication units, typically in a localized area such as a home or office. Another name for the fixed wireless terminal is Mobile Broadband Router (MBR). Fixed wireless access serves, e.g., to provide an end user with fixed line services by utilizing a wireless technology, e.g., GSM, UMTS/high-speed packet access (HSPA)/wideband code division multiple access (WCDMA), SAE/LTE, code division multiple access (CDMA), or worldwide interoperability for microwave access (WiMAX) technologies. Fixed wireless terminals offer a cost efficient way to provide high speed data, voice and fax services to small office/home office and residential users. One non-limiting example of wireless technology providing the backhaul connection, as described below, is the SAE/LTE technology mentioned above. However, the concepts described herein apply equally well to other technologies, such as UMTS/HSPA/WCDMA and WiMAX, for example.
FIG. 1 shows various aspects of fixed wireless access (FWA) and an example fixed wireless terminal (FWT). The fixed wireless terminal device shown in FIG. 1 is, for example, located in an end user's home or office, and normally remains in the same location essentially all the time. That is, there is essentially no real mobility related to the fixed wireless terminal itself except for “nomadicity”, e.g., the ability of the FWT to be powered off in one place, moved to another location, and then powered on again, and except for “vicarious portability”, e.g., the fact that the FWT can be fixedly carried or installed in a moving object, such as a train, bus, or car, for example.
Typically a fixed wireless terminal such as that illustrated in FIG. 1 provides local connectivity and services for end user equipment located in the home or other location using, for example, wireless local area network (WLAN)/WiFi™ or Ethernet as the media. In addition, the fixed wireless terminal may provide support for multiple legacy services. For example, black phone, e.g., good old fixed phone, or fax may be connected to the fixed wireless terminal. The fixed wireless terminal is then directly connected to the mobile operator's radio access and core networks, and may, for example, provide access towards the Internet. FIG. 1 provides a description of a generic example of a fixed wireless terminal, and it should be understood that different variants of fixed wireless terminals may be connected to different mobile networks and thereby support different services. As used herein, a “mobile network” comprises a radio access network, which in turn may comprise a base station subsystem, and a core network, which may include a core circuit switched network and a packet switched core network.
FIG. 2A illustrates basics of “non-roaming architecture for 3GPP accesses” in a SAE/LTE case, and as such serves to illustrate how an example fixed wireless terminal may connect to a network. FIG. 2A is taken from FIG. 4.2.1-1 of 3GPP TS 23.401 V 10.3.0, which is incorporated herein by reference. FIG. 2A shows how a wireless terminal, e.g., UE or user equipment unit, is connected to the SAE/LTE network.
FIG. 2B illustrates one example of the UMTS/HSPA/WCDMA architecture with both UTRAN and core network (CN). FIG. 2B shows how a wireless terminal, e.g., UE or user equipment unit, is connected to UTRAN, and therefore FIG. 2B also shows how a fixed wireless terminal device is connected to the UMTS/HSPA/WCDMA network.
FIG. 3A shows how an example fixed wireless terminal is logically built to comprise a Home Gateway and a user equipment unit (UE) towards the SAE/LTE network, e.g., E-UTRAN network. The right side of the fixed wireless terminal of FIG. 3A is shown as a user equipment unit (UE) that uses the LTE-Uu interface towards the mobile operator's network. The fixed wireless terminal of FIG. 3A also comprises subscriber identity module (SIM) card or a universal subscriber identity module USIM card. The left side of the fixed wireless terminal of FIG. 3A is shown as a Home Gateway (GW) that provides a “Home or Residential Local Area Network (LAN)” for the devices in the Home or in the office at which the fixed wireless terminal is located.
FIG. 3B shows how an example fixed wireless terminal is logically built to comprise a Home Gateway and a user equipment unit (UE) towards the UMTS network, e.g., towards UTRAN network. The right side of the fixed wireless terminal of FIG. 3B is shown as a user equipment unit (UE) that uses the Uu interface towards the mobile operator's network. The fixed wireless terminal of FIG. 3B also comprises a SIM card or a USIM card. The left side of the fixed wireless terminal of FIG. 3B is shown as a Home Gateway (GW) that provides a “Home or Residential LAN” for the devices in the home or in the office at which the fixed wireless terminal is located.
FIG. 4 illustrates protocol architecture showing how an example fixed wireless terminal connects to the SAE/LTE network and how the other Home Devices are connected to the fixed wireless terminal. For the LTE/SAE network, only the user plane protocols stacks are used when the other Home Devices are using the connectivity provided by the fixed wireless terminal.
The fixed wireless terminal provides a “Home or Residential LAN” for the devices in the Home or in the office. For example, FIG. 1 shows a personal computer (PC) that uses WLAN to attach to the Home LAN and to connect to the services provided by the other devices connected to the Home LAN. For example, the Network Attached Storage (NAS) can contain different content like movies, music, pictures that the end user wants to access.
In the future it is more likely that primarily wireless access technologies, rather than wired technologies like Ethernet, will be employed in the Home LAN, e.g., between the fixed wireless terminal and the Home Devices. For example, WLAN, e.g., the different variants of WiFi 802.11, will likely become even more important in the future. The current estimates show that WLAN/WiFi will likely become a commodity in mobile terminals. For example, some market estimates predict that 100% all of 3G/WCDMA mobile terminals shipped in the 2011 timeframe will include WLAN/WiFi technology. Therefore it may be assumed that fixed wireless terminal devices will be able to provide Packet Switched (PS) services for mobile terminals.
However, none of the currently known fixed wireless terminal solutions or products provide the mobile terminals the possibility to use the fixed wireless terminal device and the Home LAN for mobile telephony. There is no way for the terminal to access the mobile telephony services provided by the existing Circuit Switched (CS) Core Network (CN), e.g., no way to access the services provided by the MSC and other CS CN nodes. Non-limiting examples of CS-based mobile telephony core network (CN) services that a UE may want to access include, for example, circuit-switched Short Message Services (SMS) and circuit-switched voice calls. This is a very severe limitation for the fixed wireless terminal solutions, particularly since the existing circuit switched core network services will remain and be used for a very long time in the mobile networks while the introduction of Voice-Over-PS domain services, like Internet protocol (IP) multimedia subsystem (IMS), is still waiting to happen. Therefore, providing CS-domain based mobile telephony services as an integrated part of the fixed wireless terminal solutions is important for end users, mobile operators, and vendors. The capability of handling CS-domain based mobile telephony services may very well become a very important factor for the success of the FWT solutions.
Various ways of handling CS-domain based mobile telephony services in a fixed wireless terminal context have been contemplated. One way is for the user equipment unit (UE) to use IMS/session initiation protocol (SIP) signalling towards the FWT and the FWT interworks the IMS/SIP-signalling towards CS-based mobile telephony service, e.g., towards signalling specified in 3GPP TS 24.008. But using IMS/SIP-signalling has the major disadvantage that the services provided to the user equipment unit (UE) when in the IMS/SIP domain, e.g., connected via the FWT, would be different from the services provided from the 3GPP CS domain. Any service interworking between an IMS/SIP-domain and the 3GPP CS domain is known to be extremely difficult to support in a transparent way.
Another contemplated way to handle CS-domain based mobile telephony services in a fixed wireless terminal context involves usage of the 3GPP macro network for circuit switched access and FWT for data access. In this contemplated way the user equipment unit (UE) with both circuit switched and packet switched (PS) services would be connected like a Smartphone to both the 3GPP macro network for circuit switched service and to the FWT for PS/data service. This way has several draw backs. For example, indoor voice coverage is known to be poor, especially on high frequency bands, and indoor coverage is not significantly improved, if at all, with this contemplated way of handling CS-domain based mobile telephony services. Moreover, the user equipment unit (UE) would be simultaneously connected to both the 3GPP Macro network and to the local FWT network. This has severe impact on the UE battery lifetime.